In recent years, communication terminals including smartphones, tablets and wireless access points have increased. As communication terminals performing wireless communication become popular, frequency resources are shared by many users. Therefore, as communication terminals increase, a problem such as communication interference occurs, and decrease of a communication quality such as failure of data transmission may be caused. Thus, various techniques for relieving the problem such as communication interference and securing a communication quality have been devised.
For example, according to Non-Patent Document 1, a communication device performing wireless communication supports a plurality of transmission rates. In general, a higher transmission rate allows more data to be transmitted, but easily causes disconnection. On the other hand, a lower transmission rate needs more time for data transmission, but allows easy connection. Therefore, by selecting a transmission rate used for communication depending on the status of a communication device, it becomes possible to secure a higher communication quality.
Further, as an algorithm for determining the transmission rate, for example, ARF (Auto Rate Fallback) shown in Non-Patent Document 2 is known. In ARF, when transmission succeeds consecutively a given number of times, the transmission rate is increased to perform communication at higher speeds. On the other hand, in ARF, when transmission fails consecutively a given number of times, the transmission rate is decreased to increase the possibility of success in transmission. Such control allows easier connection in a case where transmission fails a given number of times and, on the other hand, allows control so as to perform more efficient transmission in a case where transmission succeeds a given number of times.
Further, for example, Patent Document 1 discloses a wireless communication device which has a collision detection part calculating a packet collision rate from the number of times of packet collision and the number of times of packet transmission and a control part adjusting a parameter at the time of performing data transmission on the basis of the result of calculation by the collision detection part. According to Patent Document 1, adjustment of a parameter on the basis of a packet collision rate with such a configuration makes it possible to reduce interference with other communication and increase the efficiency of data transmission.
Further, for example, Patent Documents 2 and 3 disclose techniques in which one master terminal have peripheral wireless communication terminals under control in advance and thereby reduces collision of the terminals under control.    Patent Document 1: Japanese Unexamined Patent Application Publication No. JP-A 2013-005097    Patent Document 2: Japanese Patent No. 3970563    Patent Document 3: Japanese Patent No. 3634806    Non-Patent Document 1: Impress R&D, “802.11 High-Speed Wireless LAN Text, Third Revised Version”    Non-Patent Document 2: Bell Labs Technical Journal, Vol. 2, Issue 3, pp. 118-133, 1997 “WaveLAN®-II: A High-Performance Wireless LAN for the Unlicensed Band”
However, the techniques described above do not execute control necessarily in accordance with a cause resulting in decrease of communication quality. Therefore, there arises a problem that even if the techniques described above are used, a sufficient communication quality cannot be secured in some cases depending on the cause of decrease of a communication quality. Moreover, the techniques described above have a problem that a redundant process, which is not a process appropriate for the cause of decrease of communication quality, may be performed.
Further, for example, in the technique disclosed in Patent Document 1, a process appropriate for the calculated collision rate is executed. Therefore, according to the technique disclosed in Patent Document 1, there is a problem that immediacy decreases.
In performing wireless communication, it is impossible to exclusively use a frequency. Therefore, when it is attempted to apply the techniques disclosed in Patent Documents 2 and 3, it is supposed that a possibility of presence of a communication system other than the local system in the same environment is not small. In such an environment, a wireless communication terminal beyond control of the master terminal is present, so that the techniques disclosed in Patent Document 2 and 3 may be unable to reduce collision. Thus, the techniques disclosed in Patent Documents 2 and 3 have a problem that it is not always possible to reduce collision. Moreover, the techniques disclosed in Patent Documents 2 and 3 have a problem that occurrence of a fault in the master terminal causes a failure in reduction control of all the terminals under control.
Thus, there is a problem that when performing wireless communication, it is difficult to secure a communication quality and it is difficult to perform appropriate control for securing a communication quality.